XX - 1

1
Control of the SuperGrid

• Crowne Plaza Cabana Palo Alto Hotel
• Palo Alto, California, November 6-8, 2002
• Bob Lasseter
• University of Wisconsin-Madison

2
Long range assumptions

• Looking 20-50 years ahead
• Environmental issues will increase
• Pressures to reduce carbon fuels
• Address both transportation and stationary energy
  needs

3
Continental SuperGrid

• Nuclear generation (other none carbon sources of
  energy)
• Hydrogen cooled superconducting grid
• DC network (power electronics losses)

4
DC Superconducting Network

• System
• Low voltage high current superconducting network
  (unit connected generationgtDCgtdistribution)
• Issues
• Complexity of System control (100s of sources and
  100,000s loads)
• Current control
• References
• Johnson,B.K., R.H. Lasseter, F.L. Alvarado, D.M.
  Divan, H. Singh, M.C. Chandorkar, and R. Adapa,
  "High-Temperature Superconducting dc Networks",
  IEEE Transactions On Applied Superconductivity,
  Vol. 4, No.3, pp.115-120, September 1994.
• Tang, W and R.H.Lasseter, "An LVDC Industrial
  Power Distribution System without Central Control
  Unit," PECS , Ireland, June 2000.

5
How to handle load power needs
100s of rectifiers 100,000s inverters

• AC systems frequency droop
• Complexity of power flow control
• Need distributed control

6
Distributed Control Issues

• Rectifiers (generation or storage)
• Change power output depending on load.
• Share load
• Independent of number
• Inverters
• Provides stable ac voltage to the load
• Provide required power for loads
• Automatic load shedding
• Coordination is achieved through dc voltage

7
Control of injected current
Thyristor Controlled Rectifier
Assume no resistance in line (some ac losses due
to harmonics)
8
Power Dispatch on dc voltage
9
Power Dispatch on dc voltage
Load shedding area
10
Single system voltage used for load tracking
control
11
Superconducting Network

• System
• Low voltage high current superconducting network
  (generationgtDCgtdistribution)
• Issues
• System control
• Current control
• References
• Johnson,B.K., R.H. Lasseter, F.L. Alvarado, D.M.
  Divan, H. Singh, M.C. Chandorkar, and R. Adapa,
  "High-Temperature Superconducting dc Networks",
  IEEE Transactions On Applied Superconductivity,
  Vol. 4, No.3, pp.115-120, September 1994.
• Tang, W and R.H.Lasseter, "An LVDC Industrial
  Power Distribution System without Central Control
  Unit," PECS , Ireland, June 2000.

12
Current levels in superconductors
Current flow is a function of over time and
the line inductance. In steady state there is a
single dc voltage across the system(some ac
losses due to harmonics)
13
IssuesControl of grid currents

• Currents in segments are defined by past
  transients (no unique steady state)
• Issues of over-currents in segments and faults
• Adding a de-energized segment

Need current control devices for each segment
14
Superconducting Network

• Power flow control is distributed
• Network current control requires new
  devices(superconducting current transfer
  device)
• Point-to-point only transmission
• Storage needed near loads
• Ideal transport of H2
• Johnson,B.K., R.H. Lasseter, F.L. Alvarado, and
  R.Adapa, "Superconducting Current Transfer
  Devices for Use with a Superconducting LVdc
  Mesh", IEEE Transactions on Applied
  Superconductivity, Vol. 4, No. 4, pp. 216-222,
  December 1994.

15
Ratio of H2 to electricity?

• For superconductor cooling only?
• Include transportation and stationary energy
  needs?
• Generate some H2 at source and some at load?
• Two pipelines?

16
Hydrogen only grid?

• Clusters of microgrids with H2 generators
• Small generation placed near the heat and
  electrical loads allows for reduncey
• The combined heat and power efficiencies can
  approach 95
• Transportation is integral to system.
• Technology issues for H2 grid storage.

17
Hydrogen MicroGrid with CHP
Dormitory B
Dormitory A
Administrative Building
Hydrogen
Campus Owned Distribution (13.2 kV)
300 kVA
500 kVA
500 kVA
Voltage Regulator
75 kVA
To Other Campus Loads
Generator Step Up Transformer
Academic Building B
Student Union
Heat Distribution
Paralleling Bus (4.8 kV)
Communication Control Signal Path
Generator Protection and Control
1.75 MVA
1.75 MVA
1.75 MVA
Academic Building A
300 kVA
800 kVA
Load control
Heat Recovered from ICE Units
Heat Distribution
18
MicroGrids in each building

storage
Hydrogen

H2 electric generators are placed at the point
of use to provide both electricity and heat
Reference (http/certs.lbl.gov/) Integration
of Distributed Energy Resources The CERTS
MicroGrid Concept, R. Lasseter, A. Akhil, C.
Marnay, J. Stephens, A.S. Meliopoulous, R.
Yinger, and J. Eto April 2002
19
Issues

• How to distribute H2 ?
• Superconducting current control?
• Grid vs. point-to-point?
• H2 line independent from superconducting line.
• H2 microgrids

20
Possibilities

• Today
• Natural gas microgrids gt H2 base
• Point-to-point dc superconductor